In evaluating the overall performance of a motor vehicle, the tire performance is generally one of the critical and contributing performance factors measured and evaluated through such tests as speed and endurance tests. Once evaluated, tire performance can be improved by breaking down and evaluating the individual components of the tire and how those individual components work together to contribute to tire performance and ultimately motor vehicle performance.
Tires generally comprise a composite of several layers of material, such as those layers found in a conventional steel-belted radial tire. In the conventional steel-belted radial tire, the layered material that makes up the tire comprises an inner layer of “tire fabric”, a middle or outer layer of steel belts or steel cord belt plies, and in some cases an outer layer or layers of secondary tire fabric that is commonly referred to as a “cap ply” or “overlay” and generally comprises nylon or polyester cords.
In conventional tire fabric manufacturing processes, yarn is shipped to a conversion mill where it is subject to the following process: a) yarn is twisted into a greige cord (an unfinished cord), b) the greige cords are generally woven into a unidirectional fabric stabilized with fine denier “pick threads” in the weft direction, c) an aqueous dip (commonly known as a resorcinol-formaldehyde-latex (RFL) adhesive system) is applied to the greige cord, d) the dipped cord is dried, and e) the dried cord is subjected to a high energy treating step, often requiring relatively high temperatures (350-480° F.) for relatively long residence times (30-120 sec). The resulting cord is then shipped to a tire plant where it is formed (generally calendared or passed between heated steel rolls) into a cord reinforced rubber sheet which is ultimately built into tires as the underlying carcass or the cap plies that may or may not sandwich belts or belt material. For reference, typical tire “fabric” has at least 20-30 cords per inch.
In some tire embodiments, the steel belts may be either removed altogether or replaced and/or reinforced by a polymer-based belt material or other material that can meet and/or exceed the standard for the requirements of belt properties, such as a) not heat sensitive, b) relatively constant physical properties, c) inextensible and d) fatigue resistant. However, it has been generally determined that many of the replacement and/or reinforcing materials are either too cost prohibitive or too difficult to work with and therefore, steel continues to be the belt material of choice.
Several U.S. Patents discuss cap plies and their various embodiments, including U.S. Pat. Nos. 4,284,117; 4,739,814, 6,016,857; 6,082,423 and 6,016,858. Most of these patents describe changing the materials used to produce the cap plies or replacing the steel belts. None of these patents describe physically or mechanically modifying the cap plies to improve the properties of the plies once they are incorporated into a finished tire.
U.S. Patent Application Publication No. 2002/0088523 A1 published to Miyazaki et al. discloses a pneumatic tire that comprises an organic fiber cord. Although the organic cord disclosed in Miyazaki may or may not be stretched, a measure of cord stretch and modulus is much lower than the cords of the subject matter presented herein.
Therefore, there is still a need in the tire manufacturing industry for a product that may be used to form or produce a cap ply and/or a tire that can meet and/or exceed certain performance tests when incorporated into a finished tire, such as speed and endurance tests. There is also a need for this product to be cost efficient, relatively easy to manufacture and incorporated into standard or conventional tire manufacturing processes and safe to use in the finished tire and with the motor vehicle of choice.